Metal container



1-"eb.10,1937. JWQFA 2,071,030

I ME1AL CONTAINER Fi1ed July 16', 1934 .'30 j@ g6- i y;

M Z7 /7 l `QP /9 19t ,Zhi/en for Patented Feb. 16, 1937 UNITED STATES PATENT GFFICE :METAL CONTAINER Application July 16, 1934, Serial No. 735,305

3 Claims.

This invention relates to metal containers, and particularly to containers such as cans, commonly made of sheet metal such as tin, and in which comestibles such as fruit, meat, vegetables and other substances are hermetically sealed.

The housekeeper usually finds great diiiiculty in openingcans of this sort with the can openers available in most kitchens. It has been proposed partially to shear the tin cover, as in the case of sardine cans employing a key, but that is not generally practiced in cylindrical cans. It would be difcult to be certain that the pressure generated inside of the usual vegetable can, for example, Would not create too much of a stress upon the sheared line and thereby cause it to open.

Other arrangements having a line of partial shearing or a line of reduced thickness for ease in opening have also been proposed, but they have left sharp shoulders Where the metal would, if placed in exure, be likely to fail from internal pressure. They have not been practiced in containers of the type to which the present invention is directed.

The object of the present invention is to provide, in a device of the class described, a'line of reduced thickness for convenience in opening of the can, and at the same time to avoid any sharp shoulders, sharp lines or sharpchanges in thickness where the metal would, if placed in flexure, be likely to fail from internal pressure.

This object is attained, preferably, by stamping or striking the metal a blow with a punch to form a line of reduced thickness without sharp shoulders, but with a gradual change in thickness from 35 the line of reduced thickness to the full thickness of the metal. Since the weakened portion is not partially weakened at any point, it is not subject to the objections that the partially sheared metal presents. The metal is not only rendered thinner along the line of reduced thickness, but is made more or less brittle along that line.

Another and more specific object is to form the line of reduced thickness along the bottom of an annular groove at or near the outer edge of the top of the can where the can opener works. This gives the advantage of conveniencey in opening and, at the same time, maximum metal is here available .against internal pressure, and the sides of the groove strengthen or reenforce the line of reduced thickness against internal pressure. Hence, the can is no weaker against internal pressure than it was before, and, at the same time, opening of the can is facilitated.

Further objects and advantages of the present invention will be apparent from the following detailed description, taken in connection with the accompanying drawing, in which:

Figure 1 is a perspective View, in vertical section, of a metal container embodying the present g5 invention;

Figure 2* is a fragmentary vertical section showing punch and die means for producing the top of the can illustrated in Figure 1;

Figure 3 is a fragmentary view showing a.; modified form of punch and die means for forming the annular groove in the top of the can and reducing. the thickness of the bottom of this groove without sharp shoulders or the like;

Figure 4 is a perspective View in vertical section :115 showing another form of can top embodying the present invention; and

Figure 5 is a view similar to Figure 4 showing a further embodiment of the invention.

Referring to the drawing, the can or container shown comprises a cylindrical body I0 closed at the bottom at II and provided with a top I2 joined marginally to the upper edge of ythe body I0 in any suitable manner, such as by means of the ordinary double seam I3.

The body I0 and top I2 are made preferably of sheet metal, such as tin, although any suitable or preferred material may be employed within the scope of the present invention. When the top I2 is applied, the contents are hermetically sealed Within the container.

The cover or top I2, of approximately the outline shown, has an annular groove I5 at or near its margin and a centrally raised part I6 produced by the punch and die means to be presently described, or by drawing the metal initially. The bottom I 'l of the annular groove I5 upon which the can opener is designed to work is, according to the present invention, given a special treatment to do two things-first, to form an annular line I8 of reduced thickness adapted to be easily severed by the can opener without sharp corners but with a gradual change in thickness at I9, I9 from the line of reduced thickness I8 to the full thickness of the cover of the can, and second, to make the metal morey or less brittle along' this line of reduced thickness.

The groove I5 provides for receiving and guiding the can opener in its Work in opening the can and, at the same time, the annular side walls of the groove strengthen or reenforce the line of reduced thickness I 8 along the bottom of the groove against internal pressure. And with the groove I5 disposed at or near the outer margin of the cover I2 where the can opener-55 works, maximum metal is available against internal pressure so that the cover I2 is no weaker against internal pressure than it was before, and at the same time opening is facilitated.

The punch and die means shown in Figure 2 comprises the die 25 having a circular cavity 26 to receive the plate from which the top or cover I2 is formed. The die 25 has an annular groove 2'! at or near the margin of the finished cover or top I2, which groove 21 in this embodiment of the invention has an yannular flat bottom 28. The diameter of the circular cavity 26 may be substantially equal to the initial diameter of the top or cover forming plate to center the same in the die.

The circular punch 30 is recip-rocable into and out of the cavity 25, and the diameter of the punch may be substantially equal to the diameter of the cavity to be guided Vslidingly by the upstanding circular wall of the cavity. The punch 30 has an annular punch portion 32 which operates in the groove 21, and, upon depression of the punch, strikes a blow upon the part of the metal which forms the bottom II of the groove I5 in the top I2. The bottom of the punch portion 32 is rounded, as shown, or tapered slightly from the center to the side edges to form in the bottom Il of the groove the annular line of reduced thickness I8 adapted to be easily severed by the can opener and without sharp shoulders, but with a gradual change in thickness at I9, I9 from the line of reduced thickness to the full thickness of the top of the can. The annular punch portion 32 and the cooperating annular groove 2l simultaneously draw the metal inwardly from the upst-anding circular wall of thevcavity 26 to form the groove I5 in the top or cover I2.

The gradual thickening at I9, I9 from the line of reduced thickness I8 to the full thickness of the metal reenforces the bottom of the groove I5 against internal pressure, and the side walls 20V further strengthen and reenforce the line of reduced thickness I8 along' the bottom of the groove against internal pressure, the metal along the bottom of the groove I5 flowing outwardly from the line of reduced thickness I8 toward the sides of the bottom of the groove. At the same time, the metal along the bottom of the groove I5 is rendered more or less brittle.

As illustrative of the relative dimensions of a commercially practicable container embodying the present invention, the metal forming the top I2 may be of a thickness of about .010 of an inch, and with about this thickness of metal the bottom of the punch portion 32 may be formed to reduce the thickness along the line I3 to about .005 of an inch, with a gradual thickening toward the full thickness at the opposite sides of the groove. This, of course, is merely illustrative, and may vary widely within the scope of the present invention, and formation of the groove in portions o the can other than the top or cover is contemplated within the invention.

In order to remove the stamped cover or top plate I2 from the die 25, the die may be perforated and provided with pins 35 arranged to move upwardly through the perforations so as to expel the stamped plate from the die. Somewhat similar pns 36 may be provided for removing the stamped cover plate I2 from the punch 30, it being understood that the pins 35 and 36 are merely illustrative of any suitable means for this purpose.

The embodiment illustrated in Figure 3 is similar to that illustrated in Figure 2 except that the bottom of the groove 21', instead of being flat as in Figure 3, is rounded as shown, or tapered upwardly slightly toward the center at 28 to cooperate with the complementary rounded or tapered bottom 40 of the punch portion 32. In this connection, with metal of about .010 of an inch thick the center of the bottom of the groove 21 is raised about .0025 of an inch, and the center of the rounded or tapered bottom 60 of the punch portion 32 extends downwardly about .0025 of an inch to bring the metal along the line of reduced thickness to about .005 of an inch. These particular dimensions may vary within the scope of the present invention, but in Figure 2 I have shown a rounded or tapered bottom punch cooperating with a groove having a flat bottom, whereas in Figure 3 I have shown a rounded or tapered bottom punch cooperating with a groove having a complementary rounded or tapered bottom for bringing, in each instance, the metal to the desired reduced thickness along the severing line'without sharp corners or sharp changes inl thickness.

In Figure 4, the metal forming the top 42 is struck a blow with an annular punch or hammer to form an annular line of reduced thickness 43 without the annular groove, but, again, without sharp shoulders or sharp changes in thickness where the metal would, if placed in fleXure, be likely to fail from internal pressure. In this case, the gradual thickening of the metal from the line of reduced thickness 43 to the full thickness of the top I2 is illustrated at 44, 44.

The embodiment illustrated in Figure 5 is similar to Figure 4 in that it does not have the annular groove, but the line of reduced thickness 43' is reduced from the top and bottom as in Figure 3. This may be accomplished by a rounded or tapered bottom annular punch cooperating with an upwardly rounded or tapered portion in the die, the gradual thickening from the annular line of reduced thickness 43 being indicated at 44', 44.

I do not intend to be limited to the precise details shown or described.

I claim:

l. As anY article of manufacture, a metal container having a relatively deep groove provided with a bottom upon which an opener is adapted to work, the metal of the bottom of said groove being reduced in thickness along a line intermediate the sides of said groove and being gradually thickened from the line of reduced thickness to the full thickness at the opposite sides of the bottom of the groove, and the sides of said groove being disposed at generally right angles to the adjacent wall of the container to remove the stresses imposed upon the wall of the container from the line oi' reduced thickness along the bottom of the groove and to reenforce said line of reduced thickness against internal pressure.

2. As an article of manufacture, a circular sheet metal cover for sheet metal containers proivided with a relatively deep annular groove near its margin and a centrally raised part, the metal of the bottom of said groove being reduced in thickness alongi a line intermediate the sides of the groove and gradually thickened from the line of reduced thickness to the full thickness at the opposite sides of the bottom of the groove, and the sides of said groove being disposed at generally right angles to the centrally raised part of the cover to remove `the stresses imposed upon said centrally raised part from the line of reduced thickness along the bottom of the groove and to reenforce said line of reduced thickness against internal pressure.

3. As an article of manufacture, a circular sheet metal cover for sheet metal containers provided with a relatively deep annular groove neardits margin and a centrally raised part, the metal of the bottom of said groove being rounded or tapered downwardly from the sides o-f the groove to form an annular line of reduced thickness intermediate the sides of the groove, areas of gradually increasing thickness from the line of reduced thickness to the full thickness at the opposite sides of the bottom of the groove, the sides of said groove being disposed at generally right angles to the centrally raised part of the cover to remove the stresses imposed upon said centrally raised part from the line of reduced thickness along the bottom of the groove and to reenforce said line of reduced thickness against internal pressure.

JOSEPH W. FAY. 

